"When we initially designed and implemented the auction house system, the driving goal was to provide a convenient and secure system for trades. But after much review and player feedback, it became increasingly clear that despite the benefits of the AH system and the fact that many players around the world use it, it ultimately undermines Diablo's core game play: kill monsters to get cool loot.

We feel that this move along with the Loot 2.0 system being developed concurrently with Reaper of Souls™ will result in a much more rewarding game experience for our players.

The final shutdown is scheduled for 18th March 2014.

Hight and Diablo III Game Director, Josh Mosqueira also posted a video explaining the decision: